what are the characteristics/traits of a good forensic dna scientist?
TRANSCRIPT
• What are the characteristics/traits of a good forensic DNA scientist?
The Scientific Method
• A procedure used to solve problems or answer questions.
• A way of thinking and looking at the world.• A technique used to gather information and
reach conclusions.
Steps to the Scientific Method
Observation Hypothesis Experiment Conclusion
If the results do not support hypothesis
Then revise the hypothesis
Principles of Crime Scene Investigation
______ Document the scene
______ Protect the scene
______ Help the victim
______ Search the scene
______ Photograph and draw location of items of evidence
______ Transport evidence to the laboratory
______ Package evidence
Principles of Crime Scene Investigation
1. Help the victim
2. Protect the scene
3. Document the scene
4. Search the scene
5. Photograph and draw location of items of evidence
6. Package evidence
7. Transport evidence to the laboratory
Search the Scene
• Goal- “no stone is left unturned.”
• Patterns and search strategies– Squares and rectangles– Concentric circles– Pie configuration
Presumptive vs. Confirmatory Tests
• Presumptive– Sensitive– Not specific
=many false positives
• Confirmatory– Less sensitive– Specific
=few to rare false positives
Blood
• Presumptive– Luminol– Phenolphthalin– Hemastix
• Confirmatory– Takayama crystal test– ABAcard Hematrace
Luminol
Luminol
Diffusion• Diffusion- the spontaneous
tendency of a substance (solute or solvent) to move from a more concentrated to a less concentrated area.– T or F. Diffusion results in the
uniform distribution of a substance.
Spermatozoa
• Presumptive– Ultraviolet light– Brentamine reaction
• Confirmatory– Christmas tree stain– PSA or P30– Microscopy
Male Reproductive System
Prostatic urethra
Spongy urethra
Membranousurethra
23
Salivary Glands
Saliva
• Presumptive– Lugol’s reaction
• Confirmatory– Phadebas
Phadebas ® Test
Positive testNegative test
Fecal Material
• Presumptive– Microscopy for
undigested materials– Edelman’s Reagent UV
• Apple-green fluorescence
Urine
• Presumptive– UV Light– Urea
• Litmus paper
– Creatinine• Jaffe Test